This invention relates to systems and methods for secure e-mail based transactions over public networks, and more particularly to methods and systems for affording secure authenticated transactions over public networks without the necessity for a security infrastructure requiring online access during the transaction.
Many on-line services such as banking, brokerage, marketing, sales or the like, require a high degree of security and protection. This may require authentication, allowing a transmitting site to prove its identity, authorization, allowing a particular type of transaction on a particular set of data, and non-repudiation to guarantee that transactions have not been tampered with. One method of accomplishing this is through a public key infrastructure or PKI, which provides identity authentication, and non-repudiation protection. A public key infrastructure such as public key cryptography enables users of an unsecure public network, such as the Internet, to exchange data securely and privately through the use of cryptographic keys that are obtained and shared through a trusted authority. The public key infrastructure also provides for a digital certificate that can identify an individual or an organization, and a directory service that can store and revoke the certificates. However, PKI requires special software, a certain level of administrative overhead, and training. Moreover, PKI requires keys which are published and managed by a central authority for all users of this system which entails a further degree of complexity.
Another method of achieving authentication, authorization, and nonrepudiation is to use a on-line connection over a secure network connection, either within a firewall or through a privacy tunnel such as Secure Sockets Layer or Virtual Private Networking, combined with an authentication scheme such as user ID and passwords or kerberos keys issued by logging into a certification service. For example, in a traditional web-based financial transaction, the user connects to the server through a secure private channel and authenticates at log-in time by entering a password or otherwise presenting credentials established as a consequence of the user being on a network. However, this method of securing transaction requires that the user be on-line at the point in time when the transaction is authorized.
Some approaches to authentication, authorization, and nonrepudiation combine both PKI and secure, on-line access. For example, the authentication credentials for logging into an on-line service may be issued by a PKI infrastructure.
While PKI can be a solution for authentication, authorization, and nonrepudiation of transactions over unsecure public networks, and on-line connections with conventional authentication can be a solution over secure private networks, a need exists for a similar level of protection for off-line transactions without PKI. An off-line transaction is one in which a user performs the transaction while disconnected from the network, and later through a process of synchronization or routing sends the transaction to a server. An example of an off-line transaction is filling out an electronic form and mailing it in to a server. When the form is received by the server, the transaction is completed. Off-line transactions offer the advantage of being independent of network connectivity. They offer the farther advantage of being able to use any asynchronous data routing or replication process. Off-line transactions are also advantageous in that they allow a user to prepare a transaction leisurely without the necessity of being connected to the server. However, once a transaction has been prepared, to complete it the user requires the same kind of security as would otherwise be provided by a PKI or similar security system in order to protect the security of the transaction when sent over a public network. For example, if the transaction were sent using email over a public network, the contents of the message would be encrypted using a public key issued to the user, so that others could not send a similar message in the user's name. Presently, it is necessary for a user to be either connected to a server over a secure network when performing a transaction or to use a PKI approach in order to have the degree of security required by many applications.
Thus, a need exists for a method and system enabling off-line transactions with substantially the same security as PKI, without the requirement of secure network connectivity, and without the need for special PKI software to be run by the end user. It is to these ends that the present invention is directed.